Presser foot for sewing machine

ABSTRACT

A presser foot for a zigzag sewing machine for preventing the skipping of stitches in the sewing of fabrics. The presser foot is provided with a generally rectangular needle aperture having its major axis extending transversely of the movement of the fabric. The elongated front edge of the aperture has a lip preferably formed of plastic material and extending rearwardly in close proximity to the needle.

United States Patent [191 Kuromegawa [4 1 Feb. 19, 1974 i 1 PRESSER FOOTFOR SEWING MACHINE [75] Inventor:

[73] Assignee: Maruzen Sewing Machine Co., Ltd.,

Osaka, Japan [22] Filed: Apr. 27, 1972 [21] Appl. No.: 248,216

Toru Kuromegawa, Osaka, Japan [52] US. Cl. 112/235 [51] Int. Cl D05b29/00 [58] Field of Search... 112/235, 236, 237, 238, 239,1l2/240,157,158,159,150,151,140;

[56] References Cited UNITED STATES PATENTS 2,017,317 10/1935 Magney74/104 2,811,124 10/1957 Bono 112/235 2,985,126 5/1961 Rhodes 112/2353,326,159 6/1967 Boser 112/235 3,449,970 6/1969 Klatt 74/89 3,512,4905/1970 Wener 112/235 FOREIGN PATENTS OR APPLICATIONS 260,273 3/1949Switzerland 112/235 Primary Examiner-Jordan Franklin AssistantExaminer-Peter Nerbun Attorney, Agent, or Firm-Nathan N. Kraus; JosephR. Marcus; Gerald S. Schur [5 7 ABSTRACT A presser foot for a zigzagsewing machine for preventing the skipping of stitches in the sewing offabrics. The presser foot is provided with a generally rectangularneedle aperture having its major axis extending transversely of themovement of the fabric. The elongated front edge of the aperture has alip preferably formed of plastic material and extending rearwardly inclose proximity to the needle.

8 Claims, 10 Drawing Figures PAIENIEBFEBIBJQH v 3.792.675

' sum 30F 4 v PATENIEBFEBI 91m SHEET '4 BF 4 BACKGROUND OF THE INVENTIONThe present invention relates to an improved presser foot for use in azigzag sewing machine for preventing the skipping of stitches in thesewing of fabrics.

The sewing of modern synthetic soft and flexible fabrics such aspolyester knits, and the like, has been attended with problems, inparticular, the skipping of stitches during normal operation of thesewing machine. It is believed that this condition is due to acombination of factors, one of which is the relatively large area of theneedle hole normally provided in the needle plate and presser foot toaccommodate the lateral zigzag movement of the needle. In its downwardtravel the needle penetrates the fabric and the friction between theneedle and the fabric forces that portion of the fabric disposed overthe needle hole downwardly into the hole in the needle plate. In theupward travel of the needle the fabric is drawn into the needle hole ofthe presser foot. Thus, the fabric is caused to flex in the zone of theneedle hole. Accordingly, the fabric moves upwardly with the needleinstead of lying flat and permitting the needle to move relative to thefabric. As a result the thread passing through the fabric is notsubjected to the normal friction which is depended upon to form a properloop for engagement by the shuttle hook. The consequence is a skippedstitch.

l have found that the problem may be remedied by preventing the upwardmovement of the fabric into the needle hole of the presser foot as theneedle is caused to move upwardly. Thus, the required friction betweenthe fabric and the thread is established to form a proper loop forengagement with the shuttle hook. It is suggested that a simpleexpedient would be to make the width of the needle hole and the needleplate and in the presser foot approximately equal to the diameter of theneedle. Then, fabric could not enter into the needle hole of the presserfoot as the needle traveled upwardly because of the relatively close fitbetween the needle and the presser foot. This arrangement has obviousdisadvantages. Because of existing fabrication and assembly tolerancesof the machine, the needle is likely to strike the presser foot in itsdownward movement. Further, when the presser foot is caused to betilted, as when moving over a seam having double plies of fabric, theneedle may strike the edge of the needle hole of the presser foot and bebroken.

SUMMARY OF THE INVENTION One of the objects of this invention is theprovision in a zigzag sewing machine of means for preventing theskipping of stitches in the sewing of certain types of textile fabrics.

Another object of this invention is the provision of means forpreventing the fabric being raised with the upward travel of the needlethereby to insure the formation of a proper loop of the upper thread sothat it may be engaged by the shuttle hook.

Still another object of this invention is the provision of a presserfoot having an integral lip of reduced thickness extending towards thecenter line of the needle hole, the fabric engaging portion of thepresser foot being molded preferably of plastic material.

A further object of this invention is the provision of a presser footembodying the foregoing characteristics which includes adjustable meansfor accurately locating the needle hole in desired registration with theneedle so as to preclude the possibility of breakage of the needle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a fragmentary perspectiveview of a conventional zigzag sewing machine with certain parts removedto show the underlying structure.

FIG. 2 is a fragmentary vertical cross-sectional view illustrating thesewing condition which obtains when using a conventional presser foot.

FIG. 3 is a similar view illustrating the sewing condition which obtainswhen using a presser foot in accordance with my invention.

FIG. 4 is a cross-sectional view on a reduced scale taken substantiallyon line 44 of FIG. 3.

FIG. 5 is an elevational view, partly in cross-section, showing therelationship of the presser foot to the needle when the presser foot isin normal and inclined positions.

FIG. 6 is a fragmentary elevational view of a sewing machineillustrating a modified embodiment of my invention.

FIG. 7 is a cross-sectional view taken substantially on line 77 of FIG.6.

FIG. 8 is a fragmentary elevational view partly in cross-sectionillustrating another modified embodiment of my invention.

FIG. 9 is a cross-sectional view taken substantially on line 99 of FIG.8, and

FIG. 10 is a view similar to FIG. 8 and showing another modifiedembodiment of my invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, thenumeral 12 indicates the arm of a conventional zigzag sewing machineprovided with a reciprocating needle bar 11 carried on a supportingmember 13 which is arranged to swing laterally of the direction ofmovement of the fabric being stitched. The needle bar 11 carries aneedle 14 secured thereto as with a screw. Supported in the arm 12 forvertical movement is a presser bar 15 which is biased by a coiledcompression spring 16 in a downward direction. A pressure foot 17 havinga shank 18 is secured to the lower end of the presser bar 15, as with ascrew 19. Pivotally secured to the shank 18 as by a pin 21 is a footmember 20 formed preferably of suitable molded plastic material andincluding an elongated needle hole 22. It will be understood that thelength of the hole 22 is sufficient to accommodate the full lateralmovement of the needle 14 on opposite sides of a median line. The widthof the needle hole 22 conventionally is of the order of l 10th of aninch so that there is sufficient clearance to accommodate the needle toprevent contact of the needle with any part of the foot member. Thisclearance takes into account any manufacturing and assembling tolerancesof the sewing machine parts.

Referring to FIG. 3 the fabric engaging surface 24 of the foot member isprovided with a surface portion 23 which extends across the length ofthe needle hole 22 and rearwardly of the edge 31. The beveled surfaceportion 23 affords clearance or relief so that there is no pressure onthe thread by the foot member in the area immediately rearwardly of theneedle hole. Thus, there is no interference with the thread tighteningaction resulting in improved stitch formation. The foot member includesa lip which as seen clearly in FIG. 3 is integrally molded with theforward edge of the needle hole 22 and extends substantially fully alongthe length thereof. It will be seen that the lip 25 is integral with thelower portion of the edge 26 of the needle hole and of substantiallyless depth than that of the foot member 20. Thus, as seen in FIG. 3there is clearance above the lip 25 for a purpose as will be hereinafterexplained. The bottom face of the lip 25 is co-planar with the bottomface of the foot member 20 and constitutes an extension of the fabricpressing surface. As seen in FIG. 3 the lefthand edge of the lip 25terminates just short of contact with the needle 14 but slightlyoverlaps a portion of the needle hole in the plate 32. In one example ofthe present embodiment utilizing a size 14 needle having a diameter ofl/20th of an inch, the lip 25 is spaced approximately 1/ 100th of aninch from the needle 14.

The advantages of the present invention will best be understood byreference to FIGS. 2 and 3 which illustrate the prior conditions ofoperation compared to those accomplished with the present invention.

In the prior art conventional arrangement illustrated in FIG. 2 theneedle holes both in the needle plate 32 and in the pressure foot 20 areelongated transversely of the direction of the line of stitching inorder to accommodate the needle in its zigzag movement. When a softfabric is being stitched the fabric 27 tends to be pushed by the needle14 into the hole in the needle plate 32 as the needle moves downwardlyto penetrate the fabric. When the needle 14 moves upwardly the fabricportion a tends to move upwardly into the hole 22 of the foot member, inthe manner in-dieated in FIG. 2. Correspondingly, the portion of theupper thread 28 which normally would form the loop to be engaged by theshuttle beak moves with the fabric portion a with the result that theloop disappears, as illustrated in FIG. 2, or is reduced to a size whichis insufficient to be caught by the shuttle beak 30 to form a stitch. Asa result, a stitch is skipped.

Referring to FIG. 3, in accordance with my invention, the lip 25pressing down on the fabric 27 prevents the fabric from moving upwardlytogether with the needle 14 into the needle hole 22. Accordingly, thethread 28 forms a proper loop b shown by the broken lines. This loop isofa conventional size to be engaged by the beak 30 to form a properstitch.

The reason for the provision of the clearance above lip 25, as shown inFIG. 3, is illustrated clearly in FIG. 5. At the beginning of astitching sequence or when the pressure foot 20 is caused to pass over adouble seam, the presser foot 20 is caused to rock from the solid lineposition substantially to the dotted line position and the clearanceabove the lip 25 prevents the needle 14 from striking the pressure foot20. It will be noted that when the presser foot rocks in theaforedescribed manner, the lip 25 tends to move farther away from theneedle 14 to afford additional clearance thereby insuring that theneedle will not strike the presser foot with the consequent breakage ofthe needle. Further, the fact that the lip 25 has a relatively thincross-section and is formed of a plastic material minimizes thelikelihood of breakage of the needle in the event that the needle shouldaccidentally strike the lip 25. In such event only the lip would beslightly injured without breakage of the needle.

Referring to the modified embodiment illustrated in FIGS. 6 and 7, thenumeral 103 generally indicates a presser member having a substantiallyL-shaped bracket 101 which is mounted at the lower end of a presser bar102 in a conventional manner. The bracket 101 includes a horizontal legprovided with a pair of guide flanges 107 between which is received thehorizontal leg of a complementary member 133 to which is pivotallysecured a foot member 105, as by pin 106. The arm 104 is provided withan elongated slot 108 through which passes a screw 109 provided with anadjusting nut and, as will be apparent, the member 133 is adjustablymovable relative to the bracket 101. The foot member includes anelongated needle hole 110 defined by a lip and a beveled recess 112, all

similar to corresponding parts of the foot member 20,

of the first described embodiment. The lower face 113 of the foot member105 bears down on the surface of the fabric 114.

This embodiment affords means for adjusting the foot member 105 inrelation to the needle 111 so as to compensate for manufacturingvariations and tolerances. Thus, the lip 115 may be accuratelypositioned in relation to the needle 111 to obtain optimum operatingconditions. It will be understood that the foot member 105 functionsidentically as the foot member 20 of the first described embodiment andis preferably formed of plastic material.

In a second modified embodiment illustrated in FIGS. 8 and 9 the numeral201 indicates a shank member shaped substantially as illustrated andhaving means by which it may be conventionally attached to a presser bar202. The lower end of the shank 201 is received between two upstandinglugs 204 integral with the foot member 203. The lugs 204 aretransversely pierced to rotatably receive a shaft indicated generally by205. Said shaft includes a cylindrical portion 206, an intermediateeccentric portion 207, and an end threaded portion 208, with theportions 206 and 208 being coaxial. As seen in FIG. 9 the eccentricportion 207 is received in an aperture provided in the lower end portionof shank 201. The shaft 205 is provided with a knurled knob 209 and anut 210 cooperating with the threaded portion of the shaft 208. The footmember 203 similarly to the foot members of the above describedembodiments, is formed preferably of molded plastic material andincludes an integral lip 213 and an elongated needle aperture 212. Itwill be apparent that upon loosening of nut 210 rotation of the shaft205 by means of the knob 209 will effect movement of the foot member 203to adjust the position of the lip 213 in relation to the needle 211,thereby to compensate for manufacturing variations in the machine.

In another modified embodiment illustrated in FIG. 10, a shank 302 isadapted to be attached to a presser bar 301 in a conventional manner.The shank includes a downwardly extending leg 300 carrying a laterallyextending pin 305 on which is pivotally supported a shank portion 304 towhich is pivotally connected a foot member 306, as by a pin 307. Theshank portion 304 is provided with an arcuate slot 309 which is inregistration with an aperture in the shank 302. A screw 308 passedthrough the aperture and slot is provided with a nut to secure the leg304 to the shank 302 in a position of adjustment. The foot member 306 isprovided with an integral lip 311 and a needle hole 310. It will beunderstood that the adjustment of the lip 311 in relation to the needle312 may be effected by first loosening the screw 308, making anadjustment, and then tightening the same.

Each of the modified embodiments hereinabove described provides meansfor effecting an adjustment of the foot member so as to position the lipas close as possible to the needle, yet affording a minimum clearance sothat the needle may not strike the lip.

Various changes coming within the spirit of my invention may suggestthemselves to those skilled in the art; hence, we do not wish to belimited to the specific embodiments shown and described or usesmentioned, but intend the same to be merely exemplary, the scope of myinvention being limited only by the appended claims.

I claim:

1. In a zigzag sewing machine having a thread carrying needle mountedfor endwise reciprocation and for sidewise movement transversely of thedirection of reciprocation and a presser bar carrying a presser foothaving an elongated needle hole extending in directions transversely ofthe line of stitching and a medial slot in the forward portion of thefoot communicating with the needle hole, the improvement which comprisesa lip on said presser foot in one piece with said foot, said lipextending along the forward edge defining said needle hole, thecontinuity of said lip being interrupted. by said slot, the lowersurface of said lip being substantially coplanar with the face of thefoot engaging the fabric and constituting an extension of said face,said lip terminating just short of contact with the needle and having athickness which is less than that of the presser foot, said lip beingdisposed in sufficiently close proximity to said needle when the samehas penetrated the fabric to me clude the fabric being drawn into saidhole in the course of the upward movement of the needle thereby topermit the thread to form a loop for proper stitch formation.

2. The invention as defined in claim 1 in which at least the lip isformed of synthetic plastic material.

3. The invention as defined in claim 1 in which the face of the presserfoot is recessed in the area adjacent the rearward edge defining theneedle hole.

4. The invention as defined in claim 1 including means for adjusting theposition of the lip in relation to the needle.

5. The invention as defined in claim 4 in which the adjusting meansincludes relatively movable members intermediate the presser bar and thepresser foot.

6. The invention as defined in claim 4 in which the adjusting meansincludes a pair of generally L-shaped members, one attached to saidpresser bar and the other to said presser foot, each of said membershaving a rearwardly extending leg with said legs being juxtaposed butbeing relatively movable and means for clamping said legs together in aposition of adjustment.

7. The invention as defined in claim 4 in which the adjusting meansincludes a member attached at its upper end to said presser bar andattached at its lower end to said presser foot by means ofa pin havingan ec centric cylindrical portion, the rotation of said pin effectingmovement of said presser foot.

8. The invention as defined in claim 4 in which the adjusting meansincludes a pair of members, one attached to said presser bar and theother to said presser foot, said members being in juxtaposition with onemember being pivotally movable relative to the other and means forclamping said members in a position of adjustment.

1. In a zigzag sewing machine having a thread carrying needle mountedfor endwise reciprocation and for sidewise movement transversely of thedirection of reciprocation and a presser bar carrying a presser foothaving an elongated needle hole extending in directions transversely ofthe line of stitching and a medial slot in the forward portion of thefoot communicating with the needle hole, the improvement which comprisesa lip on said presser foot in one piece with said foot, said lipextending along the forward edge defining said needle hole, thecontinuity of said lip being interrupted by said slot, the lower surfaceof said lip being substantially coplanar with the face of the footengaging the fabric and constituting an extension of said face, said lipterminating just short of contact with the needle and having a thicknesswhich is less than that of the presser foot, said lip being disposed insufficiently close proximity to said needle when the same has penetratedthe fabric to preclude the fabric being drawn into said hole in thecourse of the upward movement of the needle thereby to permit the threadto form a loop for proper stitch formation.
 2. The invention as definedin claim 1 in which at least the lip is formed of synthetic plasticmaterial.
 3. The invention as defined in claim 1 in which the face ofthe presser foot is recessed in the area adjacent the rearward edgedefining the needle hole.
 4. The invention as defined in claim 1including means for adjusting the position of the lip in relation to theneedle.
 5. The invention as defined in claim 4 in which the adjustingmeans includes relatively movable members intermediate the presser barand the presser foot.
 6. The invention as defined in claim 4 in whichthe adjusting means includes a pair of generally L-shaped members, oneattached to said presser bar and the other to said presser foot, each ofsaid members having a rearwardly extending leg with said legs beingjuxtaposed but being relatively movable and means for clamping said legstogether in a position of adjustment.
 7. The invention as defined inclaim 4 in which the adjusting means includes a member attached at itsupper end to said presser bar and attached at its lower end to saidpresser foot by means of a pin having an eccentric cylindrical portion,the rotation of said pin effecting movement of said presser foot.
 8. Theinvention as defined in claim 4 in which the adjusting means includes apair of members, one attached to said presser bar and the other to saidpresser foot, said members being in juxtaposition with one member beingpivotally movable relative to the other and means for clamping saidmembers in a position of adjustment.